90909091 has 16 divisors (see below), whose sum is σ = 117779200. Its totient is φ = 68141088.

The previous prime is 90909089. The next prime is 90909101. The reversal of 90909091 is 19090909.

It is a cyclic number.

It is not a de Polignac number, because 90909091 - 2¹ = 90909089 is a prime.

It is a deceptive number, since it divides R_90909090.

It is a self number, because there is not a number n which added to its sum of digits gives 90909091.

It is not an unprimeable number, because it can be changed into a prime (90909031) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 24561 + ... + 28018.

It is an arithmetic number, because the mean of its divisors is an integer number (7361200).

Almost surely, 2^90909091 is an apocalyptic number.

90909091 is a gapful number since it is divisible by the number (91) formed by its first and last digit.

90909091 is a deficient number, since it is larger than the sum of its proper divisors (26870109).

90909091 is a wasteful number, since it uses less digits than its factorization.

90909091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52618.

The product of its (nonzero) digits is 6561, while the sum is 37.

The square root of 90909091 is about 9534.6258972232. The cubic root of 90909091 is about 449.6443131725.

It can be divided in two parts, 9090 and 9091, that added together give a palindrome (18181).

The spelling of 90909091 in words is "ninety million, nine hundred nine thousand, ninety-one".